Entomology for beginners. Entomology is the study of insects. This page provides some basic information on insects. First we look at the anatomy of adult insects, and then we will see a short story about the metamorphosis of insects. Insect anatomy.
The range rule tells us that the standard deviation of a sample is approximately equal to one fourth of the range of the data. In other words s = (Maximum â Minimum)/4. This is a very straightforward formula to use, and should only be used as a very rough estimate of the standard deviation.
Thus, the sum of the squares of the deviation from the average divided by 4 is 22.8/4 = 5.7. Remember, this number contains the squares of the deviations. To get to the standard deviation, we must take the square root of that number. Thus, the standard deviation is square root of 5.7 = 2.4. The equation for a sample standard deviation we just calculated is shown in the figure. Control charts are used to estimate what the process standard deviation is. For example, the average range on the X-R chart can be used to estimate the standard deviation using the equation s = R /d 2 where d 2 is a control chart constant (see March 2005 newsletter).